Method and apparatus for controlling combustion in multiple and single retort stokers



METHOD AND'APPARATUS FOR CONTROLLING COMBUSTION IN MULTIPLE AND SINGLE RETORT S'IOKERS Filed May 15, 1935 4 Sheets-Sheet 1 Aug. 4, 1936'. w. A. RIDDELL 2.049.976

' I NNVENTOR. w/Lwam a, aid/shee I BY 99 ATTORNEY 6 7 4 4 v 2N O I T S S w. A. RIDDELL D AND APPARATUS FOR CONTROLLING COMBU IN MULTIPLE AND SINGLE RETORT STOKER Filed May 15, 1935 Aug. 4, 1936.

- METHO 2 t e e h S S t e h s M 'INVENTOR. W/LW ia VM BY i ATTORNEY.

r w. A. RIDDELL METHOD AND APPARATUS FOR CONTROLLING COMBUSTI Aug. 4, 1936.

4 Sheets-Sheet 3 EN MULTIPLE AND SINGLE RETORT STOKERS Filed May 15, 1955 INVENTOR.

1936- w. A. RIDDELL I 2,049,97 METHOD AND APPARATUS FOR CONTROLLINQ COMBUSTION IN MULTIPLE AND SINGLE RETORT STOKERS Filed May 15,. 1935 4 Sheets-Sheet 4 7 mgi 52 INVENTOR.

Ina-1i Y 56 1 BY I I ATTORNEY Patented Aug. 4, 1936 sins 2,049,976 METHOD AND APPARATUS FOR CONTROL- LING CQMBUSTION IN MULTIPLE AND SINGLE RETORT STOKERS William A. Riddell, Frederick, Md., assignor to The General Engineering Company, Frederick, Met, a corporation of Maryland Application May 15, 193.5, Serial N0.v 21,616

2 Claims' (c1.13v 152* g invention relates broadly to furnaces and the valve; Fig. '1' is a longitudinal section taken more particularly to a method and apparatus for controlling combustion in multiple or single retort stokers.

One of the objects of my invention is to provide a method for automatically controlling the supply of air to the tuyres of a multiple or single retort stoker for insuring uniform and economical combustion.

Another object of my invention is to provide a construction of multiple or single retort stoker having means for controlling the velocity of air supplied to each section of the retorts of the Stoker and controlling the pressure on each section and by so doing preventing the air from blowing holes in the fuel bed.

Still another object of my invention is to provide a construction of balanced orspring tensioned valve system for multiple or single retort stokers by which the volume and velocity of air supplied to the sections of the retorts may be controlled.

A further object of my invention is to provide a construction of valve which may be adjustably mounted in different sections of multiple or single retort. stokers of various designs for automatically regulating the feeding of air to. the tuyeres.

A still further object of my invention is to provide a construction of counterweight or spring tensioned system for an automatic valve structure operative to control a supply of air to the different sections of a multiple or single retort stoker.

Other and further objects of my invention reside in the counterweighted or spring operated valve structure for multiple or single retort stokers as set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a side elevation partially broken away and illustrated in section and showing the balanced valve structure of my invention mounted in three adjacent sections of a retort; Fig. 2 is a fragmentary plan view of one section of a retort showing the balanced valve of my invention mounted therein; Fig. 3 is a substantially central vertical longitudinal section through the tuyre box taken on line 3-3 of Fig. 4; Fig. 4 is a transverse vertical section taken substantially on line l--4 of Fig. 3; Fig. 5 is a transverse vertical section taken substantially on line 5--5 of Fig. 3; Fig. 6 is a fragmentary transverse vertical section showing more particularly the adjustable construction of the frame which carries substantially on, line 1-1 of Fig. 8 showing the valve in closed position under excessive velocity of the air supplied to the tuyre boxes; Fig. it is a transverse vertical section showing the. valve 5 in closedv position which occurs when the fuel bed becomes thin and tends to blow out in spots over the tuyeres; Fig. 9 is a disassembled plan view showing the adjustable frame members by which the valves may be mountedin tuyere boxes of 1 Various designs; Fig. 10 shows a modified form of valve in which; the valve is. tensioned: by means of. a spring element; Fig. 11 shows a. further modified arrangement of valve for a retort wherein the valve is mounted in the extreme base of the retort; Fig. 12 is a lateral sectional view taken on. line l2..-l2; of Fig. 13 showing the. application of; my invention to. single retort stokers, the crosssectional'vi'ew being taken intermediate the length of the enclosed sections; Fig. 13 is a horizontal 20. longitudinal. sectional view taken. on line l3.l3 of Fig; 12: and showing. the arrangement. of valves in a single retort stoker for controlling theiflow of air through the tuyeresy and Fig. 14 is a vertical sectional View taken through one-of the sections of the retort. and showing the end walls which serve torenclose'the individual sections of the retort.

In the operation of a multiple or single retort stoker working under forced air pressure, difiiculty is often experienced in maintaining a uniform fire bed over the tuyres. Due to the nonuniform characteristics of the fuel and other conditions, there is a tendency of non-uniform combustion over the fuel bed. The non-uniformity of combustionoften results in the blowing out of the fuel bed in spots with the resulting loss of fuel and drop in temperature as well as the danger of exposing the tuyres and burning them out. After extended research, I have found that combustion in multiple retort stokers may be controlled by dividing the retorts into independent sections and mounting in each of the independent sections a balanced or spring actuated valve mechanism by which the air supplied to the different sections of the'retort may be automatically controlled; This structure has a distinct advantage in that should a section of the tuyeres in a single or multiple retort stoker be burned out orthrough, with an accompanying hole through which unused air would blow, the structure of my invention provides for the automatic closing off of the burned out section. Thus, a furnace may be continued in use regardless of the fact that certain sections may be. 5.

burned out. This is a great advantage in large power units where it is expensive and impracticable to shut a boiler or furnace down on short notice. The valves are each precisely balanced to insure the closing of the valves upon increase in the velocity of air flow. Each valve is independently adjustable so that it will automatically close under a predetermined increase in velocity or pressure of air. The automatic closing of the valves in the different sections of the multiple or single retorts prevents the blowing .of holes in the fuel bed and insures a maintenance of a uniform fuel bed. As the fuel bed tends to thin out at any position over the tuyeres, the velocity of air tends to increase within the area of the thinning out process, above one or more of the sections of the retorts resulting in the automatic closing of the balanced or spring tensioned valves. This operation allows the rebuilding of the fuel bed automatically and controls the uniform combustion of the fuel. I have found that the air is equalized over the entire area of the fuel bed thereby increasing the efliciency of combustion and economizing on the consumption of fuel.

I provide a uniform velocity throughout the fire bed which is equivalent to a pressure of from to 4" more or less of water as measured by a gauge. a

My invention will be more clearly understood by detailed reference to the drawings in which one of the retorts has been illustrated in Fig. 1 by reference character I supported adjacent its upper end by support 3 and adjacent its lower end by support 4. The retort forms a tuyere box on which the tuyeres 2 are mounted and over which the fuel is automatically supplied. The retort is divided into a section or sections according to my invention, which sections I have illustrated by Way of example at 5, 6 and I. The number of sections may be increased or diminished, and in illustrating the three sections I desire that it be understood that the arrangement shown is for illustrative purposes only. The sections are disposed between the lateral partition members 8 in the retort. The retort is provided with longitudinally extending inwardly directed ribs 9 which provide means for mounting the valves in each of the sections of the retort as will be more fully described hereinafter. The valves are mounted in the sections of the retort by means of an adjustable frame [0 having complementary portions H and I2, each 'of which contain peripheral outwardly directed lugs M which engage opposite sides of the inwardly. directed longitudinally extending ribs 9. Because of the fact that the portions II and [2 of the frame l0 maybe collapsed with respect to each other in substantially a telescopic manner it will be readily observed that the portions H and I2 may be inserted beneath the sections of the retort, moved upwardly therein, and then laterally expanded with the coacting lateral portions l5 of the frame ll abutting face to face and adjustable within the guides constituted by members l5a. When the portions H and I2 of the frame [0 have been moved to'their extreme extended limits the portions II and I2 are firmly secured by bolt member l1 aligned slot IS in lateral portions l5.

The frame I0 after being located in position in the section of the retort in which the valve is to be supported is rigidly secured by means of the nut and bolt l'l extending through the aligned slots l6. The'complementary sections II and [2 of the frame l0 are provided with the peripheral which extends through ribs l8 which serve as an abutment against which the valve closure member 20 is moved. The valve closure member 20 extends laterally across the frame it when in closed position. Hinge members 25 connected to the Valve closure member 20 are connected to the lugs 59 formed on the portion 12 of frame [0 by means of pins 22. The valve closure member 20 is thereby arranged to move through a circular space about pins 22 as pivots. I provide a depending support 23 secured to the portion I2 of the frame it by suitable plate and bolt connections 24. The support 23 depends downwardly in a substantially vertical direction for a distance substantially equal to the width of the valve closure member 20 and is then bent substantially at right angles and extends substantially more than midway of the center of the valve closure member 28 as shown at 25.

The extremity of the depending member at 25 serves as a pivotal support for the lever 26. The lever 26 has a relatively short arm 21 and a relatively longer arm 28. The fulcrum for the lever 26 is enlarged as shown at 29 so as to wholly encircle the portion 25 of depending member 23. Limiting stops 30 are secured on each side of the fulcrum 29 for determining the position of the pivotally mounted lever 26.

The lever 21 has the end thereof slotted as indicated at 3! to receive the end of the link 32. The link 32 is pivotally connected to the bifurcated end of lever 3| by means of link 33. The other end of link 32 is pivotally connected to valve closure member 2%! and bracket member 34 throughpin 35. Bracket member 34 is secured to the rear of the flat valve closure member 20. The lever 28 provides means for supporting the adjustable weight 35 which may be moved to selected positions and set in the selected position by means of set screw 31. By regulating the position of the adjustable weight 36 with respect to lever 28 the pressure at which the valve closure member 28 closes may be readily controlled. That is to say, by shifting the adjustable weight 36 toward the extremity of lever 28 the valve closure member 29 will remain open until the air reaches a' velocity which is greater than the velocity which would normally move the valve closure member 28 to closed position if the.

adjustable weight 355 were moved inwardly along lever 28 to provide a shorter effective lever arm. By selectively fixing the position of adjustable weight 3% on lever 23, the pressure at which the air will close the valve closure member 20 may be regulated. By reason of this flexibility of adjustment, combustion over the entire fuel bed may be maintained uniform. The increase in velocity of air in any localized area of the fuel bed is prevented from detrimentally affecting the structure of the fuel bed when employing the protective valve system of my invention. I have indicated in Fig. 4 the manner in which air is supplied to the tuyeres through the sections of the retort with the valve open. In Fig. 8 the manner in which the velocity of flow of the air is arrested has been shown with the valve closure member 20 shifted to closed position.

In Figure 10, I have illustrated a modified form of valve wherein the balanced lever mechanism is eliminated and in lieu thereof, tension members Ml inrthe form of springs are interposed be- I closed against the peripheral seat 18 in a manner heretofore described. a

Moreover, it is unnecessary that the valves be installed in a position substantially central of the sections of the retort as I may mount the valves as illustrated in Fig. 11 where the peripheral seat It which provides a seal against which valve seats is substantially in a plane with the lower limit of the retort. This arrangement facilitates installation, adjustment, and repair of the Valve structure.

By adjustment of the valves in the system of my invention, I meet various conditions required for combustion and particularly I am able to maintain a velocity of flow of air under a pressure bed ranging from one-fourth inch to four inches measured by means of a column of water. By selecting a desired pressure and velocity of flow, uniform economical combustion may be maintained.

Figs. 12 and 13 show my invention as applied to a single retort wherein the retort has been indicated generally at M with pusher bar 42 operating therein for feeding fuel which is delivered to the combustion area of the retort over the tuyeres designated generally at 3. v The tuyeres 43 are supported in predetermined relation with respect to the furnace structure 44 and above the wind box 45. The tuyeres 43 are cast with a web-like support beneath the surface which supports the fuel bed. End walls 58 which are solid in construction are provided under those tuyeres which define the limits of each section of the retort. The web-like supports for the intermediate tuyeres are perforated as represented at 55, 55 and 5E. Thus, a box-like section is formed through which air flows within the confined limits of each section. The associated valve 20, when closed, cuts off the air supply to each section and in any other intermediate position serves to contrcl the supply of air which flows through the sections of the tuyeres. Each section of the tuyeres includes means for supporting a valve carrier. I have shown the retort divided into sections above the wind box and immediately below the tuyeres at 46, e1, 13, 49, 59, 5|, 52, 53, etc. In each of these sections, there is mounted a frame structure IE3 consisting of frames H-l2 having lugs adapted to grip opposite faces of flanges 5 on wind box 65 and flanges 55 on retort ll. The frames ll and I2 which support 'the valves 25 are each similar to the frames heretofore described and are secured by bolt and nut connection I! in a manner similar to the method of mounting the valves as heretofore described. I may employ the tension spring arrangement at) as described in more detail in connection with Figure 10 or I may employ the balanced valve arrangement as described more particularly in connection with Figs. 3, 4 and 5. For the purpose of illustration, I have selected a tension spring arrangement All which shows the valves 25 normally tensioned to open position and disposed in planes inclined opposite to each other. The tension on the valves 28 is such that a predetermined velocity of fiow of air may be maintained through the tuyeres and under any conditions where an increase of pressure should occur by reason of the blowing out of the fire bed, the arrangement of valves of my invention automatically equalizes the pressure. Upon the burning out of any tuyeres, either in the multiple or single retort structure of my invention, the furnace may be continued in operation until such a time as is practical to shut down the furnace for repairs nace.

for it is possible to continue the operation of the furnacewith a: smaller number of tuyeres active and with the burned out tuyres automatically cutout so far as the escape of draft through the fuel bed 'is concerned.

In order to indicate the condition of the fire bed within the furnace at all times, I provide a gauge glass system mounted adjacent the front of the fu-rnaceincluding sets of U tubes corresponding in number to the sections of each of the retorts. One end of each U tube is connected through a pipe with a tap which I have indicated in the drawings by reference character 60. The tap 60 is located in each section of the retort below the tuyeres so that the pressure in each section may be applied to the U tube at the front of the furnace. I have shown the tap 60 in the several figures of the drawings located at such positions as will insure the advocation of pressure existing in the section of the retort to a corresponding U tube at the front of the furnace. In installations wherein there are three control valves and sections for each retort, I provide three separate U tubes to show the condition existing in the several sections of that retort. Corresponding U tubes are provided for the other sections of the retort. Suitably colored fiuid is provided in each U tube and for all normal conditions of air pressure through the tuyeres, the level of the fluid in all of the U tubes is raised to a similar level. However, should a blow-out occur in the fire bed, the pressure increases to such an extent that the valve in the section below the tuyres which have blown out is automatically closed, resulting in the dropping of pressure in that section which is immediately noted by the dropping of the level of the fluid in the associated U tube at the front of the fur- If the fire bed does not automatically rebuild under operation of the stoker and an excessive number of blow-outs occur, the operator is informed by the glass gauge system of the necessity of shutting down the furnace for repair.

I have found the method and apparatus of my invention highly effective in increasing the efficiency of operation of multiple and single retort stokers. It will be understood that the structure of the valve mechanism illustrated herein may be readily modified to allow the valve mechanism to be applied to various types of retorts and tuyere boxes. The construction selected herein for illustrating my invention is not intended as a limitation upon my invention, but

'merely for purposes of illustrating one form of my invention. For example, it is not necessary that retorts be employed which have a rib 9 secured thereto. Moreover, frames ll) are not necessarily adjustable. I may also find it desirable to pivot the valves 25 so that the Valves move in a longitudinal plane, that is, the valves may be pivoted adjacent one end and may swing downwardly into the wind box in a position to be automatically moved to closed position upon increase in pressure and velocity of flow of the air.

Thus, it will be seen that many rearrangements i from said frame structure, a balancing lever pivotally mounted on said supporting member and hingedly connected with said air valve, and an adjustable weight carried by said lever for predetermining the opening or closing of the air valve according to the velocity of flow of air through the retort.

2. An air flow control for retorts comprising an adjustable frame structure engageable with a retort, a laterally extending peripheral seat on said frame structure, a flat valve hinged adjacent one side thereof to said frame structure and swingable to a position engaging said valve seat for shutting off the supply of air to the retort, a supporting member depending from said valve seat, a lever fulcrumed on said supporting member, a pivotal connection between one end of said lever and said valve, and an adjustable counterweight on the other end of said lever.

WILLIAM A. RIDDELL. 

